HVAC Code Lookup

Ruud Furnace Code 57

Soft lockout

High pressure switch open with the inducer on high speed. On a two-stage or modulating furnace the control will usually drop to low fire and keep heating (if the low pressure switch stays closed) rather than shut off completely.

Manual wording: “HIGH PRESSURE SWITCH OPEN, INDUCER ON HIGH SPEED ... This fault indicates that the high pressure switch is open when the inducer is energized at high speed.”

Documented for: (-)97V, (-)96V

Likely causes, most common first

  1. Blockage or improper termination in either the inlet or exhaust vents
  2. The flue vent length and/or number of elbows exceeds the maximum number specified
  3. Faulty or disconnected inducer
  4. Faulty control board (inducer relay)
  5. High altitude kit not installed in areas of high elevation
  6. Loose or faulty wiring
  7. Disconnected, blocked, split or cut pressure switch hoses
  8. Wind gusts (sporadic)
  9. Faulty pressure switch

What you can safely check yourself

  • Check the outdoor intake and exhaust terminations for snow, ice, leaves or a nest.
  • Check the condensate drain and trap for a clog.
  • Power cycle once at the furnace switch after clearing any blockage.

When to call a technician

If the vent terminations are clear and 57 keeps coming back, have a technician check the inducer, pressure switch hoses and total vent length. Never jumper the switch.

A Ruud furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Sources

Other Ruud codes